Can SIBO cause fatigue?
In my experience, SIBO fatigue is very real. But does SIBO cause fatigue?
Small intestine bacterial overgrowth or SIBO is a diagnosis that is relatively new, so the medical community still has lots to learn. But if you’ve been struggling to find a cause of your unexplained fatigue, SIBO could be the answer you’re looking for.
SIBO is a condition where there is an overgrowth of bacteria in the upper part of the digestive tract. While this is a disorder that occurs in the small bowel, the effects are far-reaching.
Let’s start with a brief introduction to your digestive tract!
A quick look at your small intestine
The small intestine is the part of your digestive system located between your stomach and your large intestine. This is where the majority of food absorption takes place. If you have celiac disease, the small intestine is the organ that gets damaged by the gluten protein.
Three distinct section make up your small intestine:
- This is the initial part of the small intestine.
- It is the shortest part and is where preparation for absorption occurs.
- This is where bile and digestive enzymes from your pancreas enter the small intestine.
- The jejunum lies between the duodenum and the ileum.
- It is specialized for the absorption of nutrients.
- The ileum is the final section of the small intestine.
- It absorbs vitamin B12, bile salts, and other nutrients not absorbed by the jejunum.
- The ileum joins the large intestine.
Your small intestine serves three primary functions:
- Digestive enzymes from the liver, gallbladder, and pancreas enter the small intestine in order to help break down proteins, fats, and carbohydrates.
- Once the food is broken down by the digestive enzymes, the small nutrients pass through your small intestine and are absorbed into your blood supply.
- The presence of good bacteria (but not too much) in your small intestine creates a local immune system in the digestive tract.
- This is where your body samples allergens and passes the information on to your immune system.
Bacteria, your small intestine, and fatigue
A healthy small intestine contains relatively few bacteria – less than 10,000 bacteria per ml of fluid. This is compared to the large bowel, or colon, which contains at least 1,000,000,000 bacteria per ml of fluid.
These bacteria have a number of important roles:
- Protecting against other disease-causing bacteria and yeast.
- Absorbing nutrients and vitamins.
- Keeping your bowels moving properly. (2)
Recent research suggests that those with chronic fatigue syndrome have distinct alterations to the bacteria in their gut. (3) These microbial imbalances mean chronic fatigue sufferers are more likely to have irritable bowel syndrome (IBS). And SIBO may just be the reason for the microbial imbalance!
What exactly is SIBO?
SIBO is defined as an increase in the number of bacteria and/or changes in the type of bacteria present in the small intestine. Most often it is an overgrowth of the various types of bacteria normally found in the colon. This occurs when bacteria from the large intestine migrate upwards into the small intestine.
SIBO can also result from an increase or overgrowth in the normal bacteria of the small intestine. (4) This occurs when intestinal motility is slowed. Those of you with constipation are at an increased risk for developing SIBO. When you’re constipated, the delay in your food’s transit time through your small bowel allows those bacteria plenty of time to digest that food. If the bacteria are well fed, they multiply. This can eventually result in SIBO.
In healthy controls, the transit time of food through the small bowel should be less than two hours. (5) Compare this with a normal transit time of forty hours through your large bowel. If food moves through your small intestine at a slower rate, you’re at increased risk for developing SIBO.
This is part of the reason SIBO can be so hard to treat. Not only are there multiple types of bacteria, but many of them are also normal healthy bacteria that should be present in the body—just in a different location or a different amount.
What are the symptoms of SIBO?
The most common symptoms of SIBO include: (6)
- Abdominal pain and/or discomfort,
- Bloating and abdominal distension,
- In more severe cases, there may be weight loss symptoms related to vitamin/mineral deficiencies.
These symptoms sound very similar to what people who have IBS experience. This isn’t a coincidence. In one study SIBO was found in more than 80% of people with IBS. More surprising, the same study found that 6-15% of people have SIBO but do not have any of these gut-related symptoms. (7)
In a previous post, I discussed how fatigue and celiac disease are related. The same holds true for SIBO and fatigue. SIBO symptoms are not necessarily only in your digestive tract – SIBO fatigue is very real.
What causes SIBO?
Your body has several different ways of preventing SIBO. These include:
- Production of stomach acid so your stomach stays acidic.
- This ensures proper digestion of your food.
- Muscles that ensure food moves quickly through your small intestine.
- Developing SIBO is more likely when food spends too long in your small intestine.
- Antibodies in your intestines that kill foreign bacteria and viruses.
- A valve that keeps food moving in one direction through your small intestine and into your large bowel.
- This valve also keeps bacteria in its proper place by ensuring the bacteria from your large bowel do not migrate into your small bowel.
The causes of SIBO are usually complex and likely affect more than one of the protective mechanisms listed above. New research is showing a connection between your HPA axis and SIBO. It’s through this axis that high-stress levels can both cause and aggravate SIBO. (8)
A number of risk factors for SIBO have been identified, with some of the more common risk factors listed below: (9)
- High levels of stress,
- Celiac disease,
- Crohn’s disease,
- Prior bowel surgery,
- Type I and type II diabetes
- Multiple courses of antibiotics,
- Previous bouts of food poisoning,
- Low stomach acid
- Check out my blog post on the effects of low stomach acid for more info
SIBO’s impact on fatigue
SIBO can cause fatigue through a number of different pathways. It can cause damage to your small intestine as well as prevent the proper absorption of nutrients: (10)
- SIBO may damage the cells (mucosa) that line the small bowel resulting in “leaky gut”
- Leaky gut occurs when large protein molecules are able to escape into the bloodstream. Read more about leaky gut and if L-Glutamine helps
- A leaky gut may trigger the activated immune system found in those with chronic fatigue syndrome. (11)
- The excess bacteria may eat vitamins and amino acids before your own cells have a chance to absorb them.
- This can lead to nutritional deficiencies due to poor digestion or absorption.
- Vitamin B12 is absorbed through the lower part of your small bowel. SIBO infections can decrease your body’s ability to absorb B12.
- One of the main symptoms of vitamin B12 deficiencies is fatigue.
- SIBO often exists for a number of years undiagnosed.
- This creates a degree of inflammation within your body. In response to inflammation, your body releases cortisol. Cortisol helps decrease inflammation.
- If the inflammation continues unchecked for a number of years, the chronic cortisol secretion can result in hypocortisolism. And the number one symptom of low cortisol is fatigue!
But before you go thinking SIBO is the root cause of your fatigue, know that SIBO is more likely to be a symptom. I touch on this topic in great detail below!
Are there different types of SIBO?
SIBO comes about through two different types of bacteria: (12)
- A combination of both hydrogen- and methane-producing bacteria.
SIBO associated with hydrogen overproduction:
An overgrowth of bacteria in the small intestine may cause hydrogen dominant SIBO. These bacteria ferment unabsorbed carbohydrates before they are broken down. This fermentation creates hydrogen gas as a byproduct. In hydrogen dominant SIBO, the main symptoms tend to be loose stools and/or diarrhea.
SIBO associated with methane overproduction:
This type of SIBO is due to a microorganism called archaea. Archaea actually isn’t a bacteria but something called a prokaryote. In the gut, archaea can use the hydrogen gas produced by other bacteria and create methane gas as a byproduct. High methane levels are often associated with constipation, which may be a symptom of this type of SIBO.
How is SIBO diagnosed?
Accessing the small intestine is no easy feat. It is 6 meters (20 feet) long and lies in the middle of your body. This makes testing for SIBO very challenging. The current way to diagnose SIBO is through a breath test. In this test, you swallow a sugar solution and then collect your breath every 20-30 minutes for three hours. (13)
As this solution passes through your digestive system, the bacteria in your body ferment the solution’s sugars. If there is an overgrowth of either methane- or hydrogen-producing bacteria, the breath sample will show it. Once the test is complete, the gases in the sample are measured in a lab.
Interpreting the results
There are two possible results:
- A negative test. The breath test will show little to no increase in hydrogen or methane gas production until the solution reaches the large bowel.
- A positive test. The breath test will show an increase in gas levels early in the test and again once the solution reaches the large bowel. This is called the “double-peak”. The double-peak indicates a positive SIBO diagnosis. (14)
The breath test is far from a perfect test as the result may be negative when SIBO is actually present. But for now, it is the only test available.
If you suspect you have SIBO, make sure you are working with a practitioner very familiar with the proper diagnostic criteria. As SIBO is still a new disease, laboratories have yet to standardize control values. This means that receiving a misdiagnosis from a lab is a real possibility.
For those suffering from fatigue, SIBO could be the missing piece. It’s a treatable condition and once removed, the likelihood of your energy improving is quite high. (15)
But before you go thinking that treating SIBO is the silver bullet for fatigue, read the next section. As you’ll soon learn, SIBO may be more of a symptom than a cause of fatigue.
Is SIBO a root cause of fatigue?
Early on in my functional medicine career, I thought SIBO was the root cause of many different gut pathologies. I was confident that SIBO caused IBS. Yet whenever I treated SIBO with antimicrobials or antibiotics, my patient’s symptoms either marginally improved or didn’t improve at all.
SIBO was not a root cause of fatigue. SIBO was a symptom of fatigue. But I couldn’t explain why it was this way. It wasn’t until I did a deep dive into toxic mold illness and its connection to fatigue that I figured it oute.
The illness caused by toxic mold is known as Chronic Inflammatory Response Syndrome or CIRS. I’ve come to learn that CIRS is almost always at the root cause of chronic fatigue syndrome. And I say that with a great deal of confidence.
The effect of Chronic Inflammatory Response Syndrome (CIRS)
Studying CIRS taught me about a hormone known as melanocyte-stimulating hormone or MSH. MSH has a profound effect on pituitary end organs and the way they function. Some of the effects of lowered MSH include:
- Sleep disturbance
- Melatonin production requires MSH.
- Chronic pain
- Low MSH results in low endorphin production.
- GI problems (like SIBO and IBS) (16)
- MSH deficiency will impair the immune function in your gut making you more prone to infections like SIBO.
- MSH is required to maintain the tight junctions in your GI tract.
- Low levels of MSH = leaky gut.
- Changes to cortisol levels
- I’m sure you already know cortisol’s effect on fatigue!
- Lowered MSH results in lowered cortisol levels.
- Prolonged illness
- Lowered MSH results in a regulation of the cytokine response.
- This results in you staying sicker for longer.
These symptoms are just the tip of the iceberg for MSH deficiency. I want you to notice just how well the symptoms I listed fit with a typical chronic fatigue syndrome symptom pattern.
Should you treat SIBO for fatigue?
If you take away one thing from this post, let it be that in the context of fatigue, SIBO is a symptom, not a cause. You can treat SIBO all you want, but until you identify the underlying cause of SIBO, your fatigue will not improve.
If you’ve tried treating SIBO but found that the treatment didn’t improve your symptoms, consider that your case of SIBO could be a symptom of another underlying illness. Work with a knowledgeable functional medicine practitioner that is well-versed in mold illness.
I’ve witnessed SIBO infections resolving on their own after improving MSH levels. No antibiotics needed.
Now, I want to hear from you!
How has SIBO impacted your energy?
What sort of treatment did you find most effective?
Leave your answers in the comments section below!
Michelle Robbins says
Very informative! I learned new information that would potentially help me figure out years of frustration! Not sure that I have CRPS but CIRS as you described from mold exposure 20 years ago at work. Now I am trying to test for SIBO because I have all the symptoms including leaky gut.